“Field Interlacing” is a well-known technique in television technology and is used to increase the perceived flicker frequency and update rate of a display. In this technique, two “field” images of half the display vertical resolution are combined together to form one “frame”. There is a 180° phase lag between consecutive fields so that one field image comprises odd lines of an original image and the other field image of each frame comprises even lines of the original image at a different time. The process of capturing such images and transferring them to a display as two fields is known as “interlacing” and FIG. 1 of the accompanying drawings illustrates how two such fields are scanned to form an interlaced image. This type of interlacing uses two input images from the same image source with a time difference therebetween.
US2003/0117349 discloses an example of an interlacing technique where odd fields are used for one image of a stereo pair and each even fields are used for the other image. It is known to use this technique in combination with liquid crystal shutter glasses in order to provide a stereoscopic display. Such shutter glasses are synchronised in operation to the display of the fields such that the left eye shutter is open, say, for the odd fields and closed for the even fields whereas the right eye shutter is open for the even fields and closed for the odd fields. However, interlacing is limited to combining images at line resolution and the effective reduced update rate of the display results in visible flickering of the displayed images.
FIG. 2 of the accompanying drawings illustrates an interlacing technique, for example as disclosed in U.S. Pat. No. 6,573,928, for use in autostereoscopic displays. In such displays, right eye and left eye images are spatially multiplexed on a single display screen, which cooperates with a parallax optic to create left eye and right eye viewing regions. When an observer's left and right eyes are disposed in the left eye and right eye viewing regions, respectively, a 3D image is perceived without the need for any viewing aids.
Each 2D image is formed as rows and columns of groups of red, green and blue pixels constituting composite colour pixel groups. Each image comprises n columns of such composite colour groups and spatial multiplexing is provided by interlacing the individual colour component pixels from the same row in the left and right images to form an interlaced image. As illustrated in FIG. 2, interlacing may be performed in two steps.
In the first step, the composite colour groups from the left and right images are interlaced in each line so as to alternate with each other. In the second step, some of the individual colour component pixels are moved to achieve the final interlaced image. In particular, the central colour component pixel of each group is moved to the central position in the next group to the right. This results in spatial multiplexing so that the pixels cooperate with a parallax optic to form the left and right eye viewing regions.
Software is available, for example as disclosed in U.S. Pat. No. 6,594,083 and on the internet at http://www.imtech.cse.dmu.ac.uk/{tilde over ( )}mcf/ilace and http://www.promagic.net, for interlacing multiple images for use with lenticular-type 3D displays.
A common feature of these known techniques is that the interlacing pattern is intrinsic to the display. In particular, interlacing is performed by dedicated hardware or software in accordance with the fixed and specific requirements for the particular application.